On 01/13/2011 03:20 PM, Robert Collins wrote: > On Fri, Jan 14, 2011 at 11:13 AM, Alex Rousskov > <rouss...@measurement-factory.com> wrote: >> On 01/13/2011 02:18 PM, Robert Collins wrote: >>> Have you considered just having a caching-only local DNS server >>> colocated on the same machine? >> >> I am sure that would be an appropriate solution in some environments. On >> the other hand, sometimes the box has no capacity for another server. >> Sometimes the traffic from 8-16 Squids can be too much for a single DNS >> server to handle. And sometimes administration/policy issues would >> prevent using external caching DNS servers on the Squid box. > > This surprises me - surely the CPU load for a dedicated caching DNS > server is equivalent to the CPU load for squid maintaining a DNS cache > itself; and DNS servers are also multithreaded?
A general-purpose caching DNS server usually does more than Squid does, so I would not be surprised if it uses more CPU cycles. And even if a super-optimized DNS server is fast enough, administration/policy issues may still prevent it from being installed on Squid boxes. And FWIW, BIND multi-threading is rather poor. I am sure there are faster servers out there, but the "most popular" one may not work as fast as the DNS server component of SMP Squid. Thank you, Alex.